1. Field of the Invention
The present invention relates to a working machine and, more particularly, to a composite working machine for milling and turning purposes.
2. Description of the Related Art
A first conventional working machine in accordance with the prior art shown in FIG. 1 comprises a base 1, an x-axis track 4 mounted on base 1, a y-axis track 3 mounted on the x-axis track 4, and a cutter 2 mounted on the y-axis track 3. The x-axis track 4 is movable in the X-axis direction, and the y-axis track 3 is movable in the Y-axis direction. The y-axis track 3 is inclined relative to the x-axis track 4, and an angle of about thirty degrees (30°) is defined between the y-axis track 3 and the x-axis track 4. However, the y-axis track 3 is not perpendicular to the x-axis track 4 so that it is difficult for a programmer to write the working program and difficult for an operator to calibrate the working precision.
A second conventional working machine in accordance with the prior art shown in FIG. 2 comprises a base 1a, an x-axis track 4a mounted on base 1a, a y-axis track 3a mounted on the x-axis track 4a, and a cutter 2a mounted on the y-axis track 3a. The x-axis track 4a is movable in the X-axis direction, and the y-axis track 3a is movable in the Y-axis direction. The y-axis track 3a is inclined relative to the x-axis track 4a, and an angle of about thirty degrees) (30°) is defined between the y-axis track 3a and the x-axis track 4a. However, the y-axis track 3a is not perpendicular to the x-axis track 4a so that it is difficult for a programmer to write the working program and difficult for an operator to calibrate the working precision.
A third conventional working machine in accordance with the prior art shown in FIG. 3 comprises a base 1b, an x-axis track 4b mounted on base 1b, a y-axis track 3b mounted on the x-axis track 4b, and a cutter 2b mounted on the y-axis track 3b. The x-axis track 4b is movable in the X-axis direction, and the y-axis track 3b is movable in the Y-axis direction. The y-axis track 3b is perpendicular to the x-axis track 4b. However, the y-axis track 3b is disposed at an inclined state and is inclined relative to the ground to produce a force moment so that the center of gravity of the y-axis track 3b is disposed at an unsteady state, and the y-axis track 3b is easily deformed or worn out due to the force moment produced by inclination, thereby shortening the lifetime of the working machine. In addition, the y-axis track 3b is disposed at an inclined state so that the y-axis track 3b is not operated exactly and stably, thereby causing instability and difficulty in operation of the working machine, and thereby decreasing the working precision and stability of the working machine.